Pegmantit -3 ( shortly P-3, NATO Code: Dumbo ) was the first Soviet 3D radar device that was developed at the end of the Second World War.
The station was established in mobile (P- 3M) and stationary variant (P- 3A). The mobile station was in van bodies on two trucks verlastet. Transmitting and receiving equipment were housed in a cabin. The vision device was still linear versions steering with A-Scope.
But if the vision device, an A -scope is only then a fast continuous rotation of the antenna is excluded. It is more likely that the side angle measurement was a kind Peilvorgang. The specified accuracy of 4 ° is otherwise hardly accessible by a single pair of Yagi antennas.
The elevation angle determination with an accuracy of 1.5 ° was possibly already with a goniometer, as in several follow-up models of meter -wave radar (eg the Knife Rest radar family P-8 and P -10) was used. For the purpose of determining the elevation angle of the radar unit requires two superimposed antenna planes. The phase difference between the antenna planes is a measure for the elevation angle of the target. The goniometer were two slip rings, on which the received RF pulses of the respective antenna plane produced a standing wave. Two pickup moved synchronously and compared the RF voltages on the two slip rings together. In a specific position, the high-frequency voltage difference was equal to zero, this mechanical position was associated with an elevation angle. The conversion of elevation angle in a flight altitude was dependent on distance and could be made using a nomogram.
- G. Nitschke, K.-H. Lau, "From the visual observation of the airspace for electronic air surveillance ". In: Military Affairs 7/72 - Output B ( Air Force ) Military der DDR
- Equipment and armament ( NVA)